Honing tool holder with integral in-process feed system

ABSTRACT

A honing tool holder that mounts in a rotatable spindle of a machine tool or machining center lacking a feed system, capable of holding and automatically operating an in-process adjustable feed honing tool for honing a work piece to a desired diameter or other characteristic, the feed force being adjustable with the tool on the spindle via centrifugal applied force, and further adjustable in range by restraining and releasing one or more of the weights while on the holder, or removing or adding weights, and/or a feed force profile being adjustable by replacing cams of the holder.

This application is a continuation-in-part of co-pending patent application Ser. No. 13/825,389, filed Mar. 21, 2013, which application was submitted under 35 U.S.C. 371 claiming priority to PCT/US2011/52595, filed Sep. 21, 2011, which application claims the benefit of U.S. Provisional Application No. 61/384,947, filed Sep. 21, 2010. This application additionally claims priority from U.S. Provisional Application No. 62/393,080, filed Sep. 11, 2016.

TECHNICAL FIELD

The invention relates generally to a honing tool holder, and more particularly, that is adapted for mounting in a rotatable spindle of a machine tool or machining center lacking a feed system, and is capable of holding and automatically operating an in-process adjustable feed honing tool for honing a work piece to a desired diameter or other characteristic.

BACKGROUND ART

Co-pending patent application Ser. No. 13/825,389, filed Mar. 21, 2013, and U.S. Provisional Application No. 61/384,947, filed Sep. 21, 2010, and U.S. Provisional Application No. 62/393,080, filed Sep. 11, 2016, are incorporated herein by reference in their entireties.

Machine tools and machining centers, hereinafter sometimes jointly referred to by the term “machine tool”, including, but not limited to, milling machines and the like, include rotatable spindles configured for holding tools such as milling cutters, drills, reamers, and the like, for performing machining operations, such as but not limited to, milling, drilling, boring, and reaming. Such tools are typically removably held in the spindle by tool holders, which allow quickly changing the tools, for instance, by an automatic tool changing apparatus. Honing is a machining operation that can impart a much more precise size, shape, and finish to work piece bores, but many traditional honing tools require a feed mechanism or system for adjusting a feed position and/or feed force of honing elements, e.g., abrasive stones, of the tool, in process, as those elements are urged against the surface of a bore of a work piece for honing the bore. Known machine tools and machining centers lack the required feed system or mechanism, and thus to utilize traditional in process adjustable feed honing tools on machine tools, some manner of providing a suitable feed system must be devised.

Several honing tools that have an in-process feed capability designed for use in machine tools lacking a feed system or mechanism, are known. Many machine tools have a through-the-spindle coolant delivery system, and it is known to use the pressure of this coolant to directly or indirectly force the honing elements or abrasive stones of the honing tool against the surface of the bore. Reference, Hyatt et al., U.S. Pat. No. 5,800,252, which discloses a honing tool designed for use in a machine tool having through-the-spindle coolant. By means of passages the coolant pressure is supplied directly to chambers behind the abrasive stones to provide direct force. However this type of tool allows each abrasive stone to feed independently, which has been found to lack an ability to reliably improve the roundness of a bore, which is often a goal of the honing process. In the traditional in-process adjustable feed honing tools, roundness is usually improved by having the honing elements or abrasive stones fed or moved by a single wedge element that keeps all of the honing elements or stones advancing or retracting in unison.

Reference also Becksvoort, et al., U.S. Pat. Nos. 6,739,949 B2, and 7,070,491 B2, which disclose an alternative to a traditional in-process adjustable feed honing tool, by having a wedge style feed element that is moved or fed by the pressure of coolant delivered through the machine tool spindle. These tool lack any manner of providing feedback to an operator that a finished or other particular bore size has been reached. Typically, honing is done for a set period of time or some external means of in-process bore gauging is employed to determine when the desired bore size has been reached. These inventions are only useful when installed in a machine tool that both provides through-the-spindle coolant and that precisely regulates the pressure of the coolant provided. Many machine tools do not have this capability or may only have it with some additional expense. In-process bore gauging is a possible manner of determining bore size, but requires stopping the process, or incorporation of an on the tool gauge such as an air gauge, which would require a supply of compressed air to the tool.

Mechanical alternatives to coolant powered feed are also known. Reference in this regard, Kline U.S. Pat. No. 1,998,460 directed to a grinder or hone for cylindrical surfaces that utilizes spring force to radially expand abrasive elements from a body of the tool. However, this device requires a pilot or shell fixedly carried on the machine spindle and apparatus to lower a body of the tool from the pilot or shell to expand the abrasive elements. This tool allows manually setting a feed limit, but discloses no manner of adjusting a feed force in-process or providing feedback that a finished or other bore size has been reached. Rioux U.S. Pat. No. 2,256,495 discloses a lapping tool employing a gyro wheel supported on a shaft extending transverse to an axis of rotation of the tool, the gyro wheel assumes a tilted position when not rotating and is pivotable about the transverse axis to a transverse position by rotation of the tool so as to engage mating cam surfaces to press on a wedge plunger to radially expand abrasive elements of the tool. It may be possible that the feed force could be varied by controlling the angle of tilt of the gyro wheel, presumably by controlling a speed of rotation. However, when axially stroking the tool, particularly when done forcefully, or with short, quickly reversing stroking actions, so as to generate significant axial accelerations and decelerations that will be exerted against the gyro wheel, it is believed that this would cause gyrations in the tilt angle and thus potentially unacceptable variations in the feed force. As an example, were the gyro wheel to tilt one way or the other as the tool reached the end of a stroke and reversed so as to develop significant deceleration and acceleration forces, the corresponding region in the bore in contact with the tool at that time may be honed to a greater or lesser extent than other regions, so that a non-cylindrical bore shape is formed, such as an hourglass or barrel shape, which would obviously be undesirable in many instances. The Rioux patent additionally lacks any manner of providing in-process feedback as to a feed position or feed force to an operator, including that the finished bore size has been reached.

Other centrifugally operated honing tools are known. Representative examples include flail type devices, for example sold under the brand name Flex Hone, that utilize abrasive elements at the radial outer ends of wires or strings that freely expand radially outwardly when the device is rotated. Another example are cylinder hones having abrasive elements supported about a central shaft on a freely radially expanding linkages such as scissors linkages and the like. Both of these types of hones rely largely on the mass of the abrasive elements themselves as the source of the feed force so that no greater feed force can be generated, which can be inadequate for many applications. Some allow the abrasive elements to feed independently, which has been found to lack an ability to reliably improve the roundness of a bore. As with the Rioux tool, there is no feedback of feed position or force, as visual inspection or gauging are typically relied on for determining whether the finishing operation is done.

Reference also a 2010 technical paper, titled Integration of a Honing Tool into a Combination Machining Centre, by Paffrath and Biermann, which describes a “honing” tool for use in a machine tool. However, the disclosed tool is not a honing tool in the traditional sense. It consists of stones that are moved in the manner of a boring tool radially into the wall of a bore which requires significant rigidity and therefore is ill-suited to any bore except those that are very short relative to their diameter. In contrast, traditional honing tools are self supported in the bore by their honing elements or stones and possibly shoes that contact the bore in multiple angular locations, and the tools expand by changing diameter, which offers a significant advantage in the control of size and bore geometry.

Mueckschel, et al. German Patent No. 102012216360 describes a self-contained device that may be installed in a conventional machine tool spindle with said device including an internal servo motor to provide the required feeding motion. This eliminates any dependence on the machine to deliver controlled pressurized coolant. However, in its place electrical power must be delivered to an enclosed rotating device. This technology is expensive, especially when it must be miniaturized to be contained in the relatively small space that can be allotted for a tool and tool holder that would fit in a typically-sized machine tool.

None of the above referenced prior art items discloses a manner of using traditional in-process adjustable feed honing tools on the spindle of a machine tool or machining center with an in-process feed force adjusting capability.

Thus, what is sought is a honing tool holder that provides a capability for automatically feeding the honing elements or stones when in the bore of a work piece, and for automatically stopping the feeding when a particular condition such as a bore size, is reached, to enable use of an in-process adjustable feed honing tool in a machine tool, machining center, or the like, lacking a feed mechanism or system.

SUMMARY OF THE INVENTION

What is disclosed are several embodiments of tool holders for honing and other variably displaceable surface finishing tools having variably displaceable abrasive elements, that provide a capability for automatically feeding the abrasive elements such as honing elements or stones when in the bore of a work piece, and for automatically stopping the feeding when a particular condition such as a bore size, is reached, so as to enable use of an in-process adjustable feed honing tool in a machine tool, machining center, or the like, lacking a feed mechanism or system. The tool holders of the invention can also incorporate apparatus for providing in-process feedback of parameters, such as feed position and/or biasing element position, to enable determining in-process bore size values, in-process feed forces, and the like.

According to a preferred aspect of the invention, the honing tool holder includes a body having a mounting element for cooperatively mounting the tool holder on a spindle of a machine tool for rotation therewith about a rotational axis therethrough, and a tool holding element opposite the mounting element configured and operable for cooperatively holding a honing tool for rotation about the rotational axis. The tool holder additionally includes a feed system integral with and carried on the body, configured to connect or couple to a feed element of a honing or other surface finishing tool held by the tool holding element, the feed system including a biasing element or elements configured and operable to automatically exert a feed force against the feed element to urge honing or other surface finishing elements of the tool radially outwardly relative to the tool. The biasing element or elements can be configured to automatically exert the feed force upon commencement of rotation of the spindle, or release the feed force, only upon occurrence of a predetermined event or presence of a predetermined condition, signal, etc., and in some preferred embodiments can be configured and incorporated so as not to require external electrical power supply or pressurized coolant fluid delivery or other inputs.

As non-limiting examples of manners of controlling the exertion or release of the feed force, the tool holder can be actuated to do so upon rotation of the spindle, or rotation at a certain speed; upon a certain stroking action or other axial motion by the spindle; upon contact of the tool with a workpiece; receipt of coolant feed and/or feed pressure; and/or upon receipt of a signal such as a radio signal, optical or light signal, coolant pressure signal, etc., such as in the form of a pulse or pattern of pulses, etc. As non-limiting mechanism examples, the tool holder of the invention can include a release or counter biasing element or elements that act against the biasing element or elements to prevent application of the feed force and/or feed advancement, such as a release mechanism configured and operable to automatically engage an element of the feed system to prevent the exertion of the feed force against the feed element until a predetermined condition, coolant pressure, motion, and/or signal is present. This can be accomplished using a fluid powered mechanism, e.g., a fluid actuated shuttle or other valve to control delivery of coolant pressure to release or restrain the feed mechanism; and/or a centrifugal force operated mechanism or a spring operated mechanism, that restrains and releases the biasing element or elements upon rotation of the tool holder in a certain manner or at some minimum speed and/or upon some axial movement or series or combination.

As a non-limiting examples of a biasing element or elements, this can comprise one or more springs that store energy and exert the feed force when released; one or more weights that generate a centrifugal force, either alone or in concert with another biasing element or elements such as a spring or springs, and/or gravity and/or a coolant pressure supplied force. Centrifugally generated force, as with the spring force, can be contemporaneously generated and exerted, or can be generated and stored then released at an appropriate time via a release mechanism or the like, as just described. Thus, a centrifugally generated force could be generated prior to actual honing, or release of the feed system, and then released to exert the feed force to effect actual honing. A locking mechanism can also be provided to hold the feed system in a particular setting, and could be released to allow adjustment, via a suitable mechanism, such as a coolant fluid pressure pulse, an electrical input via an RF signal, an optical or light signal, or a mechanical input, such as a programmed contact with the machine table or some other fixed object. Additionally, a battery can be externally affixed to the tool holder for powering circuitry on the holder, and manually changeable, or changeable via a machine movement to pick up and release the battery from a holding station or charger on or near the table, tool holding fixture, or on the tool changer carousel or the like. As a non-limiting example, the battery could comprise a ring that is picked up by a programmed axial movement of the tool holder and secured thereabout by a programmed force or the like. It may also be possible to recharge a battery on the tool holder using an energy input such as coolant flow through a liquid rotated generator.

As an advantage of the tool holders of the invention, adjustable feed type honing and other surface finishing tools are interchangeable between a honing or surface finishing machine and another type of machine tool not specifically designed for honing, and not including a feed system, provided only that the non-honing machine has the required spindle tool mounting connections, such as but not limited to, a tapered collet, straight collet, locking mechanism, or the like. These types of tools typically incorporate apparatus for the even feeding of multiple honing elements, and thus the invention brings this capability to machine tools not including a feed system or mechanism usable for this purpose.

As another preferred aspect of the invention, the feed system includes an apparatus configured and operable to automatically prevent radial movement of the feed element of the honing tool past a limit. This apparatus is preferably adjustable, to allow varying the limit and the extent of the feeding of the honing elements. As one preferred embodiment, the apparatus can include an external element on the body movable relative thereto for performing the adjustment. This can include, but is not limited to, a nut or gear, that can be adjusted by moving the tool holder, or by moving another element in contact with the tool holder, for example the table of a typical machine tool can be moved in an X direction and a Y direction, and the spindle is typically movable in a Z direction, so that the tool holder can be configured to be adjusted by contact with a predetermined surface incorporated onto the table by any of the X, Y, and Z movements, or a combination of those movements via programmed table and/or spindle actions, to effect a desired adjustment. Additionally, the feed force can be adjustable in a similar manner, or different manner, as desired.

As another preferred aspect of the invention, the apparatus or feed system can include a signal device automatically operable to output a signal when the feed element is at the limit. The signal can be outputted to an operator, or to the machine tool or machine tool controller, such as, but not limited to, via a radio or optical signal, to initiate stoppage of the honing cycle or operation, commencement of another operation, or other desired action. As still another preferred aspect of the invention, the signal device can comprise a suitable sensor for determining and outputting information representative of a position of the feed element, such as, but not limited to, an encoder, Hall effect sensor, resolver, or the like, so that the feed position can be outputted to the operator or machine tool controller for various purposes, via any suitable communication path such as a WAN, CAN, Bluetooth, or wireless or wired network or communications link, to enable monitoring the operation and for changing a parameter or parameters thereof.

The honing operation will typically be ceased or stopped when the bore being finished has reached a desired diameter. With honing or other finishing tools that either wear slowly or wear predictably, that bore size is directly related to a position of the feeding element within the honing tool holder. In a simpler embodiment of this invention, the feeding motion produced by the honing tool holder with an integral feed system will reach a point where a simple switch can be made to change states. Low power, battery-powered electronics integral to the honing tool holder can sense this change of state and then generate a wireless signal that is transmitted for a receiver that is in communication with the machine tool control system, so that seeing this signal it may stop the honing cycle when the desired bore size is reached.

A slightly more sophisticated embodiment replaces the switch with a position sensor or encoder of some sort. The electronics then would continually read a feed system position and wirelessly transmit this positional data to the receiver where it is either interpreted by the machine tool itself or first by an auxiliary device which then communicates to the machine tool control system. The honing cycle then is stopped when a certain target position is reached. This system has the advantage of being able to make bore size adjustments using only numerical compensations. Alternately, the embodiment that employs a switch is adjusted for bore size only by a mechanical means provided within the honing tool holder assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a representative machine tool and a honing tool holder of the invention for installation in a spindle of the machine tool, and showing a representative honing tool held in the holder;

FIG. 2 is an enlarged perspective view of the honing tool holder of FIG. 1, showing the honing tool removed therefrom to reveal mounting and feed elements thereof;

FIG. 3 is an enlarged sectional view of the tool holder, without a honing tool held therein, and in a non-preloaded state;

FIG. 4 is an exploded perspective view of upper elements of the tool holder;

FIG. 5 is a continuation of FIG. 4, showing middle elements of the tool holder;

FIG. 6 is a continuation of FIGS. 4 and 5, showing lower elements of the tool holder;

FIG. 7 is another enlarged sectional view of the tool holder, in a preloaded state representative of when installed in a spindle;

FIG. 8 is another enlarged sectional view of the tool holder, showing restraining apparatus of a feed system thereof in a released state;

FIG. 9 is still another sectional view of the tool holder, showing elements of the feed system in contact with a limit, and illustrating outputting of a signal indicative thereof;

FIG. 10 is a simplified schematic side view of the tool holder of the invention, in operation holding a honing tool and stroking the tool in a bore of a work piece;

FIG. 11 is a sectional view of another embodiment of a tool holder according to the invention, with a representative honing tool mounted thereon, and mountable on the spindle of a machine tool;

FIG. 12 is an enlarged sectional view of the tool holder of FIG. 11 with a feed system of the holder shown in a retracted (non-rotating) state;

FIG. 13 is another enlarged sectional view of the tool holder of FIG. 11, showing the feed system in an expanded (rotating) state;

FIG. 13A is an illustration of wedges having alternative cam shapes;

FIG. 14 is another sectional view of the tool holder of FIG. 11, showing one possible means of creating a communication link with a machine tool with which the tool holder is used;

FIG. 15 shows the tool holder of FIG. 11 with a cover thereof removed to show internal aspects;

FIG. 16 is another sectional view of the tool holder of FIG. 11, showing an embodiment of an adjusting mechanism thereof; and

FIG. 17 is a sectional view of the tool holder of FIG. 11, showing weights carried therewithin.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Referring now to the drawings, in FIG. 1, a conventional computer numerical control or “CNC” machine tool 10 is illustrated, including a vertical spindle 12 of well-known construction and operation. Spindle 12 is automatically controllably rotatable about a vertical rotational axis Z, and movable upwardly and downwardly along axis Z, by a controller 14 of machine tool 10, in the well-known manner. Machine tool 10 additionally includes a table 16 controllably movable horizontally along an X axis and a Y axis by controller 14, and configured and operable for supporting one or more or fixtures 18 for holding a work piece or work pieces on which work operations will be performed by machine tool 10. Controller 14 is of conventional construction and operation, and is a microprocessor controlled device automatically operable for executing a machining program for controlling spindle 12 and table 16 for performing the machining operations in the well-known manner. Such operations conventionally include, but are not limited to, milling, drilling, boring, reaming, threading, and the like. The respective operations are performed using tools specialized for the operations, which are held by tool holders insertable into and held by spindle 12, also in the well-known manner. Machine tool 10 will additionally usually include a tool changer (not shown) configured and operable for automatically inserting the respective tools into spindle 12 for commencement of operation, and removing of the tools after the operation is complete, also under control of controller 14. A honing tool holder 20 constructed and operable according to the teachings of the present invention, is illustrated as being insertable into spindle 12 for rotation and upward and downward movement thereby. Honing tool holder 20 is illustrated holding a honing tool 22. Here, it should be noted that although rotational axis Z is illustrated as a vertical axis, the present invention is also configured for operation and other orientations, including, but not limited to, a horizontal axis.

Referring also to FIG. 2, honing tool 22 is representative of a wide variety of in-process adjustable feed honing tools including an elongate, hollow mandrel 24 which receives and carries a feed or wedge element 26 for longitudinal movement therein. Wedge element 26 has one or more wedge surfaces (not shown) located within mandrel 24 and which bear against mating wedge surfaces (also not shown) on honing elements 28 extending through slots 30 through the sides of mandrel 24 at angularly spaced locations thereabout. In operation, movement of wedge element 26 longitudinally into mandrel 24 (downwardly as depicted by arrow F in FIG. 2) will cause sliding relative movements of the wedge surfaces, which, in turn, will cause uniform radial outward movement or feed of honing elements 28, as denoted by the small arrows emanating radially from elements 28. Movement of the wedge element longitudinally outwardly relative to the mandrel (opposite of direction F) will allow the honing elements to radially retract. If in a work piece bore, once the honing elements are radially moved outwardly so as to contact the surface of the bore, application of a force in direction F against the wedge element, commonly referred to as a feed force, will act to transmit a radial outward force against the honing elements, which will be exerted against the surface of the work piece bore. The honing elements will comprise an abrasive substance, in the form of a stone or layer of abrasive particles, selected to achieve a desired honing or bore finishing effect, such as, but not limited to, a particular bore size, surface finish, trueness or concentricity, shape, or the like.

Honing tool 22, like many other in-process adjustable honing tools, has a mounting end 32 of a standard shape and size suitable for insertion into and retention by a standard tool holder such as a collet. At the same time, a wedge coupler 34 on the end of wedge element 26 is connectable to a feed rod of a feed mechanism located within the spindle of the honing machine and controllably movable in direction F and the opposite direction. In typical operation, at an appropriate time or times in the honing cycle or operation, the feed rod of the honing machine will be moved in direction F relative to the mandrel of the honing tool, to bring the honing elements into contact with the surface of the bore of a work piece in which the tool is located, and the feed force applied, during relative rotation and stroking of the tool and work piece, to effect honing the bore surface. Upon completion of a desired honing step or operation, the feed rod will be moved in the opposite direction, to remove the feed force and the tool can be withdrawn from the bore, or another honing operation performed.

Feed mechanisms similar to those of conventional honing machines as just described, are not present in the spindles of other machine tools, such as milling machines, machining centers, and the like, such as representative machine tool 10 illustrated. As a result, in-process adjustable feed honing tools such as tool 22 are normally not usable with a conventional, non-honing type machine tool or machining center such as machine tool 10.

Honing tool holder 20 remedies the above shortcoming, by including an integrated feed system which has a capability to both automatically initiate feeding of the honing elements, and stop the feeding when a limit is reached. Honing tool holder 20 also has the capability to automatically output a signal indicating the reaching of the limit, such that the honing cycle or operation can be halted, altered, or other step taken. FIGS. 1 and 2 show that the tool holder 20 has a relatively large body 36 including a mounting end 38 having a tapered shank 40 made to a standard connection specification (such as, but not limited to, CAT, HSK, etc.) so as to be installable in the manner of a conventional tool holder in the spindle of a machine tool or machining center not including a feed system or mechanism, such as spindle 12 of machine tool 10 which will have a matching collet for that purpose. Mounting end 38 of tool holder 20 additionally includes a flange 42 about mounting end 38 adjacent to tapered shank 40 and adapted for engagement with a conventional tool changer operable for installing and removing tool holder 20 from a spindle, such as spindle 12. When installed in a spindle, such as spindle 12, a central axis A of tool holder 20 will be coaxial with a rotational axis of the spindle (here, rotational axis Z), and tool holder 20 will be rotatable and movable upwardly and downwardly with the spindle.

Referring also to FIGS. 3 through 10 which show elements of tool holder 20, within the top of body 36, disposed within flange 42 and adjacent mounting end 38, are elements of a feed system 44 completely contained on tool holder 20 substantially within body 36 and configured to connect or couple to a feed element of a honing tool held by the tool holding element (here, wedge element 26 of honing tool 22 via connection with coupler 34). Feed system 44 includes a biasing element 46 configured and operable to automatically exert a feed force against the feed element (wedge element 26 of tool 22) via a feed rod assembly 100 (described in detail below) to urge honing elements 28 of the tool radially outwardly relative to the tool. Feed system 44 additionally includes a release mechanism 48 configured and operable to automatically engage an element of feed system 44 to prevent the exertion of the feed force against wedge element 26 until a predetermined condition occurs, which here is initiation of rotation of tool holder 20.

Biasing element 46 of feed system 44 includes a feed spring assembly 50 which consists of coil springs 52 and 54 concentrically held in a telescoping housing 56 having inner and outer tubular pieces or segments 58 and 60. Mating lower and upper flanges 58 and 60 on these telescoping housing pieces cooperatively engage when tool holder 20 is not mounted in a spindle, to contain and limit the expansion of feed spring assembly 50. A lip or shoulder around the upper end of inner segment 58 retains the upper end of spring 52, and the upper end of spring 54 is retained by flange 62. Feed spring assembly 50 has a variable position spring retainer or seat 66 threaded on its outside diameter so as to be threadedly received in the bottom end of outer segment 60 of housing 56. This contains the lower ends of springs 52 and 54 and allows for adjustment of the feed force. In FIG. 3 (with the tool holder not installed in the machine tool spindle) the feed spring assembly 50 is thus limited to its full expansion. Therefore, even though there is some preload on springs 52 and 54, all of the spring force of those springs is restrained by flanges 62 and 64 being in contact. As a result, when tool holder 20 is not installed in a spindle, the feed force delivered via feed rod assembly 100 to the wedge coupler and honing tool is zero.

Although the embodiment of assembly 50 here shows utilization of two nested springs 52 and 54, it should be understood that it is contemplated that many options will be available. One or two springs, or more springs can be used, and the springs can have various spring rates and be of various constructions. One set of springs will probably not cover the wide range of feed force that may be needed to cover all applications. As a result, tool holder 20 is built with a certain limited range of feed force based on the springs selected for the spring assembly 50. It is contemplated that, with some disassembly these springs can be changed in the field to equip tool holder 20 with a different range of feed force if required or desired for a particular application. As an alternative or in addition to spring power, biasing element 46 can comprise a different source of force, such as, but not limited to, a centrifugally powered powering means, such as radially centrifugally driven weight or weights.

Here, it should also be understood that the weight of the internal moveable components of tool holder 20, particularly, feed rod assembly 100, would by itself produce a feed force that would keep the honing tool mounted thereon from being retracted. To prevent this, a retraction spring 68 disposed about outer segment 60 of housing 56 resiliently holds the internal components in the retracted state shown in FIG. 3.

FIG. 7 shows tool holder 20 when installed in a machine tool spindle such as spindle 12. As tool holder 20 is installed in the spindle, a lower face 70 of the spindle will depress a feed force actuator 72 fixed about an upper end of inner segment 58 of housing 56 of spring assembly 50 and having radially outwardly extending ears located in slots 74 in tapered shank 40 but not flange 42. The upper end of feed force actuator 72 thus protrudes sidewardly from the tapered shank and is movable downwardly within slots 74 by the contact with the spindle to compress springs 52 and 54 beyond their preloaded state of FIG. 3. This also lets the spring force be transmitted to the components below (flanges 62 and 64 are no longer in contact). However, the spring force is still restrained from being transmitted via feed rod assembly 100 to the wedge coupler by release mechanism 48, as discussed next.

It can be observed in FIG. 3 that below feed spring assembly 50, release mechanism 48 includes a pair of restraining pins 76 that are received in grooves 80 in opposite sides of an upper feed rod 78 of feed rod assembly 100. This restrains axial movement of upper feed rod 78 and thus transmission of the feed force of the springs 52 and 54 through the feed rod assembly 100 to a honing tool held by holder 20. Restraining pins 76 are carried respectively in a pair of weights 82 of mechanism 48 that are urged radially inwardly toward and into grooves 80 by a set of intentionally weak restraining springs 84.

FIG. 8 shows tool holder 20 as the spindle rotation begins. By centrifugal force, weights 82 will move rapidly radially outwardly to the inner circumferential surface of body 36, as denoted by associated small arrows. Restraining pins 76 now clear grooves 80 in feed rod 78, and springs 52 and 54 are free to push the moveable internal components of feed spring assembly 50 down against feed rod assembly 100 and thus to the honing tool to commence feed motion, as illustrated in FIG. 9. Restraining pins 76 are mounted in bearings to minimize the centrifugal force (and hence the rotational speed) needed to overcome the friction of the members contacting weights 82. On the bottom side of the weights there are also preferably provided linear roller bearings to reduce friction. (The rollers and bearings cannot be seen in these FIGS.)

The feeding motion will progress downward as transmitted by feed rod assembly 100 while machine tool 10 rotates and strokes spindle 12 upwardly and downwardly, and with it, tool holder 20 with honing tool 22 in the bore 96 of a work piece 98 held on table 16 of machine tool 10, as illustrated in FIG. 10. The feeding motion in the tool holder reaches a point that a limit switch 86 is contacted as shown in FIG. 9 (here by a feed adjusting element 106 of feed rod assembly 100). Switch 86 is part of a sealed unit 88 located within body 36 and containing batteries 90, a circuit 92 and an LED 94 (see also FIG. 6), configured and operable for outputting a signal, denoted by arrow S, indicative of feed system 44 having reached a predetermined settable feed limit. When switch 86 is contacted by element 106 it closes the circuit 92 to provide power from batteries 90 to LED (and/or optionally an RF transmitter) to send the signal S to a receiver of, or in connection with, controller 14 of machine tool 10 as an indication that the final size and/or other characteristic of a bore 96 of a work piece 98 being honed (FIG. 10) has been reached. Controller 14 then stops the honing cycle, e.g., by stopping spindle rotation and by withdrawing honing tool 22 from the work piece bore, or performs some other programmed command.

When tool holder 20 is removed from spindle 12 to a tool changer or tool storage location (not shown), then feed force actuator 72 is no longer held depressed by the spindle face 70 and retraction spring 68 will cause upward retraction of feed rod assembly 100 of feed system 44, which will allow restraining pins 76 to once again engage upper feed rod 78, such that the feed assembly will be restrained in the position of FIG. 3. If tool holder 20 is desired to be used to hone multiple bores in succession, without removal from spindle 12, then a different embodiment of this tool holder can be provided where the reset of the feed can occur via some other controlled machine tool motion.

Bore Size and Feed Force Adjustment

The feeding motion of tool holder 20 will always stop in a consistent location relative to the tool holder. This coupled with the immediate response of controller 14 of machine tool 10 causes the honing process to always stop with the wedge element of a honing tool held by the holder in a consistent position which creates a repeatable honed bore size or other characteristic. To adjust this final honed size or other characteristic, and/or to adjust for the wear of the abrasive honing elements of the honing tool, feed rod assembly 100 (which here comprises upper feed rod 78, a lower feed rod 104, and feed adjusting element 106), within tool holder 20 must be lengthened or shortened. This is accomplished by means of the feed adjusting element 106 which has a threaded hole 108 therethrough which threadedly receives the upper end of lower feed rod 102 which is threaded for this purpose. Adjusting element 106 additionally has an adjusting gear 110 about its outer circumference, and a retaining flange 112 on its upper end. Gear 106 engages a pinion 114 that in turn engages a ring gear 116 at its lower end. Ring gear 116 is fastened to a feed position adjustment nut 118 rotatably disposed about the lower end of body 36, so that a measured turn of nut 118 will rotate ring gear 116 to rotate pinion 114, which in turn will rotate adjusting gear 110, to threadedly engage lower feed rod 102 to move it upwardly or downwardly within and relative to feed adjusting element 106. Adjusting element 106 is connected to upper feed rod 78, such that the upward and downward movement of lower feed rod 102 will also be relative to upper feed rod 78, so as to effectively shorten or lengthen feed rod assembly 100, which will translate to adjustment movements of a wedge element 26 coupled to lower feed rod 102 via coupler 104, which will adjust final bore size achieved by honing elements 28 of a tool held by holder 20.

In the setup and adjustment of a honing operation, the feed force applied to a wedge element of a tool held by holder 20 must often be adjusted and/or optimized. The feed force of tool holder 20 is generated by springs 52 and 54 of biasing element 46, which can be compressed to a greater or lesser degree to generate the feed force required. As discussed above, seat 66 is threaded into outer segment 60 of housing 56 of feed spring assembly 50. It is prevented from rotating by a keyed rod 120 that extends through the center of seat 66 and is fixed in shank 40 of the tool holder. Housing 56 has a gear 122 disposed about outer segment 60 that is engaged by smaller feed force adjustment gears 124 that protrude though slots 126 through the side of body 36. These protruding gears 124 can be turned to cause a rotation of housing 56 within and relative to body 36, which in turn will move seat 66 axially to compress or relax springs 52 and 54.

As a non-limiting example, the feed force adjustment can be automated by fastening a small segment of gear rack to a fixed location somewhere on a machine tool, such as on table 16 of machine tool 10 so that by a controlled motion of the table, one of adjustment gears 124 of the tool holder can be made to engage the rack and rotated by a controlled relative movement of the tool holder and rack by a required to effect a desired adjustment in the force. This can happen, for instance, as part of the honing process setup or at anytime in between honing cycles as directed by a machine control program or an operator.

As another non-limiting example, holder 22 can include a feed force adjusting nut 128 disposed for rotation about body 36, having an internal ring gear 130 engaged with gears 124, such that, rotation of nut 128 will effect rotation of gears 124 and the adjustment of the feed force in the above described manner. This can be accomplished by engagement of parallel surfaces of nut 128 with a pair of parallel planes 144 disposed at a suitable location adjacent to table 16, as shown in FIGS. 1 and 2, and controlled rotation of the tool holder (it should be noted here that parallel planes 144 are not shown to scale).

Honing tool holder 20 is preferably assembled in a suitable manner using appropriate fasteners, such as, but not limited to, screws 132, threaded rings, snap rings, and other common fasteners. This allows convenient access to batteries 90 and circuit 92, and to springs 52 and 54, for service and replacement.

Just above a collet nut 134 on tool holder 20, an access hole 136 is provided as one possible means for an operator to access and release coupler 104 to install or release a honing tool wedge coupler 34 of a honing tool.

Referring now to FIGS. 11-18, a second embodiment of a tool holder 200 constructed and operable according to the teachings of the invention is shown. FIG. 11 is a general cross section of the tool holder, which includes a connection piece 201 made to fit a particular type of machine tool spindle connection. The piece 201 can be made to any standard connection (e.g. CAT, or HSK) or can be customized for any machine tool spindle, as discussed in regard to mounting end 38 and tapered shank 40 of holder 20 above, and tool holder 200 can be mounted to and removed from a machine tool spindle in the manner discussed above. Connection piece 201 is fixed to a housing 202, which is fixed to a central body 203, which is fixed to a lower body 204. These four pieces form the structural frame of the tool holder 200 and rigidly connect the honing tool to the machine tool spindle.

Honing tools having ranges of bore diameter and bore length for a variety of applications can be held by the tool holder of the invention. A typical representative tool 20A is shown including a tool body 205, tool 20A holding a representative abrasive stone assembly 206. A wedge 207 is free to move axially within the tool body 205. Connection to the tool holder is made in two locations. The tool body 205 is fixed to the lower body 204 by screws (not shown) or some other connection means such as described above in regard to tool 22. The wedge 207 connects to the feed rod 215 by means of a T-slot type connection 208 or by any other convenient connection that will axially join the wedge to the feed rod.

In this embodiment, the biasing element comprises a weight or set of weights 209 that are normally drawn together toward the center of the holder 200 by extension springs 210. When the holder 200 rotates with the machine tool spindle rotation, centrifugal force acting on the weights 209 will force them apart against springs 210, that is, radially outwardly, and the holder is constructed to restrain the weights for radial movement only to facilitate this purpose, and to minimize influence of the stroking action of the tool on the feed force.

Attached to the weight 209 is a wedge piece 211 which transmits the radial motion of the weights 209 into an axial motion via follower rollers 212 or bearings on a feed carriage assembly 213 that is part of the feed system of the tool holder 200. There can various methods of translating radial motion into axial motion, any number of which could be employed here as an alternative according to the invention.

The feed system feed carriage assembly 213 is an assembly of parts, one of which is a gear 214 which includes a threaded inside diameter. These engage with mating threads on the feed rod 215. Therefore as the carriage assembly is pushed downward (as oriented in FIG. 11), the feed rod 215 pushing on the honing tool wedge 207 is also pushed down, thereby creating the feeding force and motion required for proper honing tool operation.

When spindle and device rotation stops, the centrifugal force will be absent and the springs 210 will retract the weights 209 toward the center of the tool holder 200 and retraction spring(s) 216 will force the feed carriage assembly 213 upward. By its connection to the honing tool wedge 207, that motion will retract that wedge and honing stones 206 will likewise be retracted by various means (not shown) internal to the honing tool such as a retraction spring or springs. In this retracted state the honing tool 20A will be able to enter another bore that is to be honed.

FIGS. 12 and 13 respectively show the tool holder 200 in the retracted (non-rotating) state and the expanded (rotating) state. (These FIGS. do not include the honing tool.) By contrasting these FIGS., it can be seen how the weights 209, move outward radially under centrifugal force, imparting axial force and motion via the wedges 211, the follower rollers 212 and the feed carriage assembly 213 of the feed system. This motion and the resulting expansion of the abrasive stones in the honing tool will continue until the feed carriage assembly comes against a hard stop 219.

To reduce inefficiencies that could make the honing feed force unreliable, the motion of the weights 209 is supported partly by linear bearings 217 on top and rollers 218 below so as to be radial only.

The wedges 211 need not have flat surfaces. In fact these are effectively cams that can be profiled to provide the required amplification and constancy of feed force. Taken as a system, the mass of the weights, the properties of the springs 210 and 216, and the profile of the wedges 211 will produce an output force that is a function of the radial position of the weights 209 and/or the axial position of the feed carriage assembly 213. By proper design these can produce a constant output feed force, an increasing force, a decreasing force, or any desired force level and profile, including, but not limited to, as a function of radial position of the weights 209. Referring also to FIG. 13A, as non-limiting representative examples of alternative cam surfaces of wedges 211, a wedge 211A having a straight cam surface is shown; a wedge 211B having a concave cam surface is shown; a wedge 211C having a cam surface that is a combination of two curves or a straight section and a curve is shown; and wedge 211D having a convex cam surface is shown, any combination of shapes being also contemplated. It is envisioned that tool holders 200 of this embodiment of the invention can either be built using wedges and springs that properly match the requirements of the honing application, or even that the user may be provided with additional wedges and springs that they can interchange as needed to change the operating characteristics of the device.

FIG. 14 shows the tool holder 200 in cross section from a different angle to show one possible means of creating a communication link with the machine tool, controller or other external device with which the tool holder 200 is used. The machine tool program needs to somehow know when to stop the honing cycle. A very simple method is to just hone for a set time or number of strokes. This method would require no communication between holder 200 and the machine. However, it is contemplated that most users would want to hone until a certain bore size has been reached. When abrasive stones wear very slowly or consistently, this bore size can be known as a certain position of the feed rod 215 and/or of the feed carriage assembly 213. As the feed carriage assembly 213 approaches the hard stop 219, a link 220 is engaged. Link 220 bears against a precision switch 221. When the feed carriage assembly 213 reaches a preset position just before the hard stop 219 the switch 221 will change states initiating the first step in the process of communicating with the machine tool control system.

The switch 221 and the other electronic components are housed behind a sealed protective cover. FIG. 15 shows the tool holder 200 with the protective cover removed. The circuit is comprised of the switch 221, a battery 222 and a communication device which here is a radio 223 that emits an RF signal. Also envisioned but not shown is some conventional means of charging the battery 222. This could include an inductive coil or a connection for a wired charging device. The radio 222 will have a receiving counterpart either integral to or connected to the machine tool control system. The change of state of the switch 221 prompts an immediate radio signal representative of the honing feed system reaching it final position. A receiving radio accepts this transmitted data and using serial or other communication techniques, transfers the data to the machine tool's control system. A converter may be used to translate this data to the format of the industrial network used by the machine tool's control system. Non-limiting examples of the machine tool's network include EtherCat, CC Link, and Profnet. The machine tool control system will then act on the received signal as part of the machine control program. This involves stopping the looping sub program, which moves the tool holder 200 and attached tool in and out of the bore, stopping the spindle and then taking steps to remove the tool from the honed bore.

The switch communication as a simple “cycle complete” signal to the machine control is only one way to achieve the required control. Although not shown, it should be easy to see how link 220 could be fixed to the feed carriage assembly 213 and the position of both could be sensed by a position sensor replacing switch 221. In this case the radio 223 would send continuous positional data to the receiver on the machine tool allowing the machine tool control system to determine a honing cycle stop point numerically and/or utilize positional data for display or programming purposes. As non-limiting examples, the position sensor can comprise an encoder such as a linear encoder, rotary encoder, a resolver, or a Hall effect device. As a simplified embodiment, as an alternative to the radio, the signal device could comprise an optical device such as a signal light, e.g., LED, and/or an audible alarm.

The abrasive honing stones of stone assembly 206 are subject to wear and honing can work in a range of diameter, so a means to adjust the tool holder 200 can be provided so that the honing cycle stop position, as sensed by the switch 221, corresponds to the required final diameter or some other size of the honing tool. FIG. 16 is a cross section of the tool holder 200 at a plane that shows one possible embodiment of this adjustment means. To make such an adjustment a nut 224 is integral with, or fixed to a ring gear 225 and these are mounted in a manner such that they can be rotated relative to the tool holder. This relative rotation of the ring gear 225 will impart a rotational move to a pinion 226 engaged with the feed gear 214, which in turn imparts a rotational move of the feed gear 214. Since the feed gear 214 is captured axially in the feed carriage assembly 213, a rotation of this gear, having internal threads, will impart an axial adjustment to the feed rod 215.

A manual means of accomplishing this is to apply a wrench to the nut 224 while the tool holder 200 is locked from rotation either by the machine tool or by some other means. However, the adjustment does not need to be manual. A program can be written for the machine tool so that, when commanded, the tool holder 200 mounted in the spindle is moved to some place where at least one flat of the nut 224 bears flatly against a mating surface such as explained above in regard to the first embodiment. Then a programmed rotation of the machine tool spindle will result in the same adjustment described above. The nut 224, bearing against at least one surface will be constrained to rotate while the tool holder 200 is rotated by the spindle, thus creating the required relative motion. The mechanical ratio of nut rotation to axial feed rod movement to abrasive stone expansion can be a parameter stored in the machine tool as part of the control program, so that an operator can simply command the machine tool to adjust the honing tool diameter by a specified amount. This is explained in greater detail above and is applicable here.

With all other things held constant the amount of feed force applied to the honing tool is dependent on the mass of the centrifugal weights and the speed of rotation. The best speed of rotation for honing tool is roughly a function of the bore diameter. This can present a dilemma as to whether the spindle speed should be selected for the desired surface velocity at the abrasive stone to bore interface or whether it should be selected for the optimum level or magnitude of feed force. As mentioned above, a means exists to build the assembly with components (weights, wedges and springs) to achieve the desired operating characteristics, such as a range or ranges of magnitude of the feed force. However, often adjustments to operations can be required when the honing tool is already installed in the machine tool and rebuilding the tool holder assembly would cause an undesirable delay. For this reason there is provided a mean to adjust the amount of the mass to be uses to generate the magnitude of the centrifugal force. FIG. 17 shows a cross section through the region of the tool holder 200 where the weights 209 are located. The primary driving weights 209 are referenced in other FIGS. and are held together—radially inwardly disposed, when there is no rotation by the springs 210. Fixed to the primary weights are some retaining arms 227 that extend to where they can be engaged by auxiliary weights 228. When free to move, and under spindle rotation, the auxiliary weights 228 will impart their centrifugal force to the retaining arms 227, thereby adding to the total mass in play and transmitting force to the wedges 211 (FIG. 11). However, a restraining means is provided by way of inserting pins into restraining holes 229. Such pins can be inserted through the exterior of the tool holder 200 so they are easily installed or removed even while the tool holder is held by the machine tool spindle. The weights may be in play or restrained in any combination so as to create a variety of values for the total mass that generates the centrifugal force. By this means the tool holder 200 is easily configured so that the speed that will create the desired feed force is also within an optimum range of speed for the honing tool with regard to surface velocity.

Once the tool holder 200 is configured for this expected range of operating speed and force, further performance adjustments can be made through the control of the machine tool. An increase in spindle speed will both increase surface velocity at the bore and increase the feed force via the increased centrifugal force. This has the advantage of being intuitive to an operator: To make the honing process go faster (i.e. remove the material faster) all one has to do is to run the spindle faster. Likewise a decrease in spindle speed will slow the process down.

Honing Process Control

In addition to the bore size and feed force feed adjustments that must be made by the means described above, the machine tool with which tool holder 200 of the invention is used must also be programmed for the reciprocating motion of a typical honing cycle. That programmed cycle must be allowed to continue until a signal is received from the transmitter on the tool holder, e.g., LED, an RF device, or the like. Additionally, the program should include logic to stop a cycle after a maximum time has been reached as an indication that the abrasive of the honing tool are worn out or no longer in a condition to cut effectively.

The control program should also allow for bore size compensation as follows: A manually entered tool comp would adjust the tool size accordingly. A known approximate abrasive wear rate entered by the operator would result in an automatic adjustment of the tool by that amount before each honing cycle. An external gauging device (air gauge, or similar) could feed back information to the machine control system for purposes of adjusting tool size and possibly adjusting the stroke of the honing cycle.

The routine of adjusting the tool size should also include some programmed machine motions. For example, the tool holder can be brought into engagement with a set of parallel planes 142 located at an accessible location on or adjacent to table 16 of the machine tool as shown in FIGS. 1 and 2, to engage feed position adjustment nut on the outside of the tool holder and then the spindle must be rotated by the proper amount to effect the desired adjustment. The wedge angle of the tool and ratio of the internal gearing, or a factor representative of these values will be needed to accurately calculate the proper rotation angle.

Depending on a number of factors, the tool holder with tool installed may be large enough that it may not be able to be kept in the tool magazine of the machine tool if present. It may need to reside in a nest on the table that is away from the work piece but reachable by the spindle. Such a nest could be designed to include the parallel planes 142 to always engage the nut on the tool holder, so that any tool size compensation could be made by a programmed spindle rotation just after it has grasped the tool holder but before it has removed it from its nest.

Advantages

Advantages of the tool holder of the invention as embodied by tool holder 20 and the centrifugal force operated embodiment 200 include that the tool holder has an integral system for sensing a final feed position and sending a signal immediately when that position is reached. The feed position is equivalent to the wedge position in the honing tool and therefore implies a consistent final bore size. When used with honing elements such as abrasive stones that have minimal or consistent stone wear, this will produce close bore size control.

The tool holder's connection to the honing tool is identical to a honing machine spindle so that any tools may be used interchangeably in a honing machine or any other machine tool equipped with this tool holder.

This honing tool holder does not require a machine tool that is capable of providing through-the-spindle coolant with variable and controlled pressure.

As the abrasive stones or other honing elements wear, the internal feed rod must be adjusted. As noted above, the nut on the outside of the tool holder can be turned relative to the body of the tool holder to lengthen or shorten the effective length of the internal feed rod, e.g., using parallel planes 142. This will be accomplished by programmed motion of the machine tool which will set the tool holder into a “nest” that mates with nut 118, illustrated in FIGS. 1 and 2. (E.g. like a traditional open-end wrench fixed to some location on the machine tool table.) The machine tool will then rotate the spindle (with the tool holder) by a precise angle corresponding to the amount of feed adjustment required. As another advantage, a “window” in the side of the tool holder exposes LED 94 (visible or infrared) or a radio frequency transmitter. When the internal feed rod reaches a position corresponding with the final bore size, a change of state of the switch will be made and a signal will be transmitted. A receiver connected to the machine tool control system will use this signal as a trigger to stop the honing cycle.

In light of all the foregoing, it should thus be apparent to those skilled in the art that there has been shown and described embodiments of a novel tool holder for a honing tool with an in-process feed adjusting capability. However, it should also be apparent that, within the principles and scope of the invention, many changes are possible and contemplated, including in the details, materials, and arrangements of parts which have been described and illustrated to explain the nature of the invention. Thus, while the foregoing description and discussion addresses certain preferred embodiments or elements of the invention, it should further be understood that concepts of the invention, as based upon the foregoing description and discussion, may be readily incorporated into or employed in other embodiments and constructions without departing from the scope of the invention. Accordingly, the following claims are intended to protect the invention broadly as well as in the specific form shown, and all changes, modifications, variations, and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention, which is limited only by the claims which follow. 

What is claimed is:
 1. A honing tool holder, comprising a body having a mounting element for cooperatively mounting the tool holder on a spindle of a machine tool for rotation therewith about a rotational axis therethrough and axial stroking movements, and a tool holding element opposite the mounting element configured and operable to cooperatively hold a honing tool for rotation about the rotational axis; and a feed system carried entirely on the body, comprising a feed rod assembly supported for axial movement within the body and configured to connect to a feed element of a honing tool when held by the tool holding element, to control radial movements of honing elements of the tool, and a centrifugal force operated mechanism cooperatively engageable with an element of or connected to the feed rod assembly to control axial movement thereof, the centrifugal force operated mechanism including at least one weight restrained so as to move substantially only radially and configured to be moved radial outward by centrifugal force generated thereby from rotation of the tool holder about the rotational axis to exert an axial force against the feed rod assembly.
 2. The honing tool holder of claim 1, wherein the at least one weight is biased against a radial extending surface within the body for the radial movement therealong.
 3. The honing tool holder of claim 2, wherein the at least one weight is biased against the radial extending surface by an element or elements of the feed rod assembly.
 4. The honing tool holder of claim 3, comprising at least one bearing disposed between the at least one weight and the element or elements of the feed rod assembly to reduce friction therebetween.
 5. The honing tool holder of claim 1, comprising at least one biasing element urging the at least one weight radially inwardly.
 6. The honing tool holder of claim 1, further comprising a signal unit carried on the body and including a circuit including at least a battery, a switch, and a signal device, configured to activate the signal device to output a signal when the feed rod assembly reaches a selectable limit.
 7. The honing tool holder of claim 6, wherein the signal comprises a light emission.
 8. The honing tool holder of claim 6, wherein the signal comprises an RF emission.
 9. The honing tool holder of claim 6, wherein the circuit is additionally configured to output signals representative of positions of the feed rod assembly.
 10. The honing tool holder of claim 9, wherein the positions are representative of an axial position of the feed rod assembly.
 11. The honing tool holder of claim 9, wherein the positions are representative of a radial position of the at least one weight.
 12. The honing tool holder of claim 1, wherein the at least one weight comprises a wedge having a cam surface cooperatively engaged with an element of the feed rod assembly to control the axial movement thereof.
 13. The honing tool holder of claim 12, wherein the cam surface has a curved shape portion.
 14. The honing tool holder of claim 13, wherein the curved shape portion is concave.
 15. The honing tool holder of claim 13, wherein the curved shape portion is convex.
 16. The honing tool holder of claim 12, wherein the cam surface comprises at least two portions inclined at different angles relative to the axial direction.
 17. The honing tool holder of claim 12, wherein at least the wedge having the cam surface is removable from the holder and replaceable with a wedge having a cam surface having a different shape or angle.
 18. The honing tool holder of claim 1, comprising a plurality of the weights and at least one restraining element carried on the body and configured to restrain one or more of the weights from the radial movement.
 19. The honing tool holder of claim 18, wherein the restraining element is movable to release the one or more of the weights to allow the radial movement thereof.
 20. The honing tool holder of claim 18, wherein the restraining element is selectably movable to release a certain one or ones of the weights. 